To quantitatively and noninvasively evaluate common carotid atherosclerosis in a series of patients, we measured the stiffness parameter p, which represents the mechanical properties of the vessel. /3 was calculated from the relationship between blood pressure and the diameter of the artery as measured by an ultrasonic, phase-locked, echotracking system. Increases in the severity grade of atherosclerosis as subsequently determined at autopsy were correlated with increased Rvalues in 60 common carotid arteries (r=.68).C ommon carotid atherosclerosis has been reported to precede cerebral atherosclerosis.1 -2 Therefore, evaluating the severity of sclerosis in the common carotid artery may prove to be a useful prognosticator for the development of cerebrovascular sclerosis in asymptomatic individuals. Early detection of this condition can help to reduce the risk of cerebrovascular accident. Atherosclerosis causes structural changes in artery walls that alter their physical properties. The stiffness parameter /3 proposed by Hayashi et al 3 is one quantitative index of the elastic properties of large arteries. /3 can be calculated from the measurements of blood pressure and arterial diameter. Although advances in ultrasound technique have made it possible to visualize common carotid arteries, their quantitative measurement has only recently been developed. Nakayama and Sato 4 have designed an ultrasonic measuring method of arterial wall movement that uses a phase-tracking system. Moreover, Yoshimura et al 5 have developed an ultrasonic Doppler flow meter with this system that allows transcutaneous measurement of the arterial diameter and its pulsatile change. We calculated f3 from the measurements of blood pressure, arterial diameter, and its pulsatile change. A few clinical studies have included measurements of /3, 67 but no previous study has compared clinical studies with pathological findings.The aim of this study was to define the relationship between fi of the common carotid artery and the severity grade of atherosclerosis on the basis of postmortem pathological analysis. These findings may serve as reference data for noninvasively diagnosing atherosclerosis.Received August 17,1993; revision accepted December 9,1993. From the Departments of Preventive Medicine (T.W.) and Internal Medicine IV (K.K., K.F., K.I., E.T., T.F., T.U., and S.Y.), The Jikei University School of Medicine, Tokyo, Japan.Correspondence to Takashi Wada, MD, Department of Preventive Medicine, The Jikei University School of Medicine, 25-8 Nishi-shinbashi 3-chome, Minato-ku, Tokyo 105, Japan.Patients with f) values greater than 13 had a pathological diagnosis of atherosclerosis in the common carotid artery. The sensitivity of this discrimination ratio was 80%, and the specificity was 80% as well. Thus, /3 shows promise as a useful diagnostic indicator for detecting asymptomatic common carotid atherosclerosis. (Arteriosder Thromb. 1994;14:479-482 MethodsHayashi et al 3 analyzed the behavior of arterial walls by assessing changes in vess...

To evaluate the possibility of quantitatively diagnosing carotid and cerebral atherosclerosis noninvasively, we measured common carotid flow volume in 60 sides (30 patients), using an ultrasonic quantitative flowmeter, and then compared these findings to the severity score of carotid and cerebral atherosclerosis as determined at autopsy. Stenosis decreased common carotid flow volume in the carotid and cerebral arteries. Increases in the severity score varied inversely with reduced flow volume, which was high in inverse correlation (r= -0.696). Patients with flow volumes of 8.5 ml/sec or greater did not have stenosis greater than or equal to 75%, whereas all patients with flow volumes of 6.4 ml/sec or less had stenosis greater than or equal to 50%, with 45% of these having stenosis greater than or equal to 75%. These pathological findings confirm that the common carotid flow volume reflects the degree of carotid and cerebral atherosclerosis present and that the lower limit of common carotid flow volume in healthy subjects is 6.5 ml/sec (Stroke 1991^22:319-323) U ltrasound has advanced the noninvasive diagnosis of carotid and cerebral atherosclerosis, but quantitative measurement only recently has been possible. Our ultrasonic quantitative flow measurement system has made it possible to measure noninvasively and quantitatively the absolute blood flow volume in the common carotid artery that constitutes the input end of the cerebral arteries.

The vessel wall properties of the common carotid artery have been noninvasively and quantitatively assessed with an ultrasonic instrument. Stiffness parameter beta, which represents the mechanical properties of the vessel, was calculated from the relationship between blood pressure and the diameter of the artery. There are no reports that quantitatively assess wall properties in Takayasu's arteritis. The authors compared, in vivo, the vessel wall properties of the common carotid artery in 14 patients with Takayasu's arteritis versus those in 60 normal subjects (controls). They measured changes in the inner diameter of the artery between systole and diastole with an ultrasonic, phase-locked, echo-tracking system. Beta was significantly higher in Takayasu's arteritis than in normal subjects (better than a 99% confidence interval). The findings for each decade were as follows: 3rd decade (20s): 35.7 +/- 28.9 vs 5.01-6.46, P=0.0001; 4th decade (30s): 19.5 +/- 9.71 vs 6.09-7.80, P=0.02; 5th decade (40s): 26.2 +/- 11.3 vs 7.26-9.28, P = 0.0001; 6th decade (50s): 19.1 +/- 4.27 vs 8.66-11.25, P = 0.0001. Takayasu's arteritis significantly impaired the mechanical performance of the common carotid artery. Thus, beta shows promise as a useful diagnostic indicator of Takayasu's arteritis.

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